Tofacitinib, chemically known as (3R,4R)-4-methyl-3-(methyl-7H-pyrrolo[2,3-d]pyrimidin-4-ylamino)-β-oxo-1-piperidinepropanenitrile, is represented Formula I. Tofacitinib citrate, a janus kinase inhibitor, is approved as XELJANZ® tablets for treatment of rheumatoid arthritis.

Various intermediates and processes for preparation of tofacitinib are disclosed in patents like U.S. Pat. No. 7,301,023 and U.S. Pat. No. 8,232,394. The prior art processes are time consuming, tedious and laborious. The ensuing product obtained in these processes may contain impurities, the separation and removal of which pose as a challenge, which may require multiple purification steps thereby reducing the product yield.
Presently, we have developed a novel process and novel intermediates for preparation of tofacitinib and salts thereof.